Cephalometric investigations concerning the geometry of the viscerocranium of human anencephalic fetuses.

Cephalometric investigations were carried out on 16 macerated skulls of anencephalic fetuses aged around 6 months and compared with the values obtained from a group of 18 normally developed specimens. The skull geometry of the anencephalic fetuses was different from normal proportions: anencephalic fetuses showed a clear mandibular prognathism, and a maxilla tilted in anterior direction. The values describing length of maxilla and length of the anterior cranial base, and NS-Ba angle were found to be within the normal range. From the results it can be concluded that the defective development of the forebrain seems to have no effects on the length development of the anterior cranial base although it does influence the form of the surrounding bony structures. The formation of the mandibular prognathism cannot be brought into direct connection with the defective brain development.